pulsar/negative_backoff_policy.go

// Licensed to the Apache Software Foundation (ASF) under one
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// to you under the Apache License, Version 2.0 (the
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// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
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// under the License.

package pulsar

import "math"

// NackBackoffPolicy is a interface for custom message negativeAcked policy, users can specify a NackBackoffPolicy
// for a consumer.
//
// > Notice: the consumer crashes will trigger the redelivery of the unacked message, this case will not respect the
// > NackBackoffPolicy, which means the message might get redelivered earlier than the delay time
// > from the backoff.
type NackBackoffPolicy interface {
	// The redeliveryCount indicates the number of times the message was redelivered.
	// We can get the redeliveryCount from the CommandMessage.
	Next(redeliveryCount uint32) int64
}

// defaultNackBackoffPolicy is default impl for NackBackoffPolicy.
type defaultNackBackoffPolicy struct{}

func (nbp *defaultNackBackoffPolicy) Next(redeliveryCount uint32) int64 {
	minNackTimeMs := int64(1000 * 30) // 30sec
	maxNackTimeMs := 1000 * 60 * 10   // 10min

	if redeliveryCount < 0 {
		return minNackTimeMs
	}

	return int64(math.Min(math.Abs(float64(minNackTimeMs<<redeliveryCount)), float64(maxNackTimeMs)))
}